/Engine/Source/Runtime/Slate/Public/Widgets/Layout/SMenuOwner.h
For menu widgets, tells the owner widget about a currently active pull-down menu
void SetSummonedMenu ( [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SMenuAnchor](API\Runtime\Slate\Widgets\Input\SMenuAnchor) > InMenuAnchor )